July 16, 2016

Matthew A. Schrager1, James Hilton1, Richard Gould1, & Valerie E. Kelly2

1 Department of Integrative Health Science, Stetson University, DeLand, FL, USA.
2 Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA.

As the population of over-65 year-olds increases worldwide, a growing public health issue of age-related declines in functional mobility (i.e., the ability to move from place to place, navigate obstacles in the environment, and participate in activities of daily living such as standing up out of a chair, bending over to pick up an object) is emerging. Possible non-pharmacologic countermeasures, such as tai chi or nutritional interventions, may be helpful in addressing this trend. Recent research suggests that the polyphenolic compounds contained in foods such as walnuts, grapes, strawberries, and blueberries may benefit older persons by lowering oxidative stress (i.e., the production of free radicals which must be counteracted by the antioxidants in the body) and inflammation. Building on similar research in rats and mice, the current study is the first to investigate possible effects of blueberry supplementation on measures related to functional mobility in older humans.

Participants were randomly assigned to the blueberry or placebo group. The blueberry group was supplemented for 6 weeks with 2 cups per day of flash-frozen blueberries. The blueberry group was compared to a placebo group who for 6 weeks consumed a daily serving (~450 mL) of a commercially available carrot juice drink. Carrot juice was selected as a placebo because of its perceived health benefits and lack of anthocyanins, which are a class of polyphenols responsible for the rich blue color in blueberries and known from various studies to possess potent antioxidant and anti-inflammatory properties.

Subsequent to a 6-week blueberry supplementation period, within-group improvements were found in measures such as usual walking speed and improved performance (i.e., foot placement and gait speed) during two “adaptive” or challenging balance-related tests. Relative to a control group, foot placement accuracy during a complex, dual-task adaptive gait test also improved. The dual-task gait test required walking barefoot at a self-selected comfortable pace within a narrow, 6.1-m-long path, both with a concurrent cognitive task (i.e., reciting the days of the week in reverse order) and without. It is well established that this sort of dual tasking becomes much more challenging with aging, which can then lead to increased falls risk as older persons become more distracted and more likely to commit a misstep while walking.

Although the results of this study are preliminary, they demonstrate the potential benefits of, and the need for, greater exploration of blueberry supplementation as a cost-effective, nonpharmacologic countermeasure to the worsening public health issue of diminished functional mobility. Future studies should use a larger sample size, a longer intervention period, and more sophisticated, biomechanically based measures of daily function to better assess potential benefits of blueberries on functional mobility.

Along with enhanced general nutrition and physical activity (e.g., resistance, balance, and other forms of challenging/adaptive training), blueberries may be an important component of maintaining functional mobility and independence, as well as quality of life, in an increasingly large population of persons over 65.

This article is a summary of an article published in Applied Physiology, Nutrition & Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.

Original Article

Schrager, M., Hilton J., Gould, R., Kelly, V. 2015. Effects of blueberry supplementation on measures of functional mobility in older adults. 2015. Appl. Physiol. Nutr. Metab. Appl. Physiol. Nutr. Metab. 40(6):543-49, 10.1139/apnm-2014-0247